closes #348

When the list contains a lots of applications many requests are made for
dynamic views (e.g. heapdump, flyway, logfile, ...). With this commit
the availability check for these views is deferred until the user opens
toggles the dropdown. This should lead to far fewer requests.

fixes #346

Additionally the url list is not anymore overlapped then having a lot of
tabs for the detail views.

fixes #347

With this commit the support for Turbine is completly revised. From now
on Turbine is supported via a separate module and is integrated as top
level view.

closes #306

 * Since the hystrix.stream incorrectly handles HEAD requests we had to change
   the detection for the hystrix-endpoint to a GET request.
   Issue https://github.com/Netflix/Hystrix/issues/1369

 * We need to improve Zuul's SimpleHostRoutingFilter and SendResponseFilter to
   close the underlying socket when an error occurs when writing the response.
   I hope that the code can be removen when my PR gets merged.
   Issue https://github.com/spring-cloud/spring-cloud-netflix/pull/1372

Fixes #290

In case a hystrix.stream does'nt sends any data and just a ping the endpoint is
not detecet correctly and the ui get unresponsive. The problem is that the sent
"ping:" chunk doesn't triggers the message event listener.
So instead we use a simple HEAD-request to get the header and status.

fixes #276

closes #237

By using the netflix/hystrix-dashboard this module allows you to view the
metrics from hystrix/turbine in the spring boot admin server. This module needs
to be added explicitly.

closes #147